How to Use the Lob MCP in Pydantic AI

Q: How do I add the Lob MCP Server to my Pydantic AI agent?

Install the MCP extra package and initialize MCPToolset with your Vinkius server URL. Pass this toolset into the toolsets argument of your Pydantic AI Agent constructor to register all 21 tools.

Q: Can I use Pydantic AI to track sent letters via Lob?

Yes. The agent calls listletters or getletter to fetch tracking numbers and delivery dates. The returned JSON is parsed directly into typed Python objects for safe handling.

Q: How do I manage HTML templates for letters?

Your agent can use createtemplate to register layouts and listtemplates to retrieve them. Pydantic AI ensures the merge variables passed to createletter match the template's expected schema.

Bring strict type safety to physical mail operations by integrating Lob with your Pydantic AI agents.

See Vinkius in Action

Works with every AI agent you already use

…and any MCP-compatible client

MCP Servers - Free for Subscribers

Connect Lob MCP to Pydantic AI

Create your Vinkius account to connect Lob to Pydantic AI and route execution through our secure gateway. The platform manages server hosting, runtime updates, and security layers. Configuration requires no manual server provisioning.

GDPR Free for Subscribers

Setup Lob with Pydantic AI

Ask AI about this MCP

ChatGPT

Claude

Perplexity

Type-safe address validation in Pydantic AI

The Lob MCP Server exposes `verify_us_address` and `autocomplete_us_address` to clean and standardize physical delivery coordinates. Your agent passes messy inputs to these tools and receives strictly typed address payloads in return. If the address verification tool returns unexpected data formats, Pydantic AI raises a validation error immediately. This prevents your Python application from writing corrupted address records to your database or sending mail to invalid locations.

Send verified letters and postcards with Pydantic AI

The `create_letter` and `create_postcard` tools let your agent generate physical mail pieces using HTML templates. The agent maps your internal data structures to Lob's required parameters, ensuring perfect alignment before dispatch. By using `create_template` and `get_template`, your agent manages reusable layouts safely. If a template schema changes, the runtime validation catches mismatches before the agent attempts to trigger a print job.

Secure check issuance with runtime model validation

The `create_bank_account` and `create_check` tools allow your agent to register funding sources and mail physical checks. Every bank routing number and account field is validated against strict Pydantic models before the MCP tool execution. You can audit your financial transactions by calling `list_checks` and `get_check`. Because every response is validated at runtime, you can trust that your payment tracking data matches your application schemas exactly.

Setup guide

Set up Lob MCP in Pydantic AI

Prerequisites

Python 3.10+ installed
pydantic-ai-slim[fastmcp] package
Active Vinkius subscription with a valid endpoint token

1

Install Pydantic AI with FastMCP
Run pip install "pydantic-ai-slim[fastmcp]". The FastMCP toolset replaces the deprecated MCPServerHTTP class with full protocol support.
2

Configure the FastMCPToolset
Pass a JSON-style config dict to FastMCPToolset with your Vinkius URL. Replace [YOUR_TOKEN_HERE] with your token from cloud.vinkius.com. Supports Streamable HTTP, SSE, and Stdio transports.
3

Create and run your agent
Pass the toolset to Agent(toolsets=[toolset]) and call agent.run(). Swap openai:gpt-4o for any supported model — Anthropic, Google, Mistral, or Groq.

agent.py

from pydantic_ai import Agent
from pydantic_ai.toolsets.fastmcp import FastMCPToolset

toolset = FastMCPToolset({
    "mcpServers": {
        "lob-mcp": {
            "url": "https://edge.vinkius.com/[YOUR_TOKEN_HERE]/mcp"
        }
    }
})

agent = Agent(
    "openai:gpt-4o",
    toolsets=[toolset],
    system_prompt="You have access to Lob tools.",
)

result = await agent.run("List recent Lob transactions")
print(result.output)

Get your connection token →

Independent Platform Disclaimer: Vinkius is an independent platform and is not affiliated with, endorsed by, sponsored by, verified by, or otherwise authorized by Lob. All third-party trademarks, logos, and brand names are the property of their respective owners. Their use on this website is strictly for informational purposes to identify service compatibility and interoperability.

Why Choose Vinkius

Vinkius connects your tools to AI with real-time monitoring and automatic cost savings — all from one dashboard.

Connect Lob now

Real-time monitoring

Live

visibility into every interaction

Connect your favorite tools to your AI and see exactly what's happening — every request, every response, in real time.

Built-in savings

60%

lower AI costs

Vinkius compresses data between your apps and your AI automatically. Lower bills every month — no configuration required.

Single dashboard

One

place for every integration

Every tool your AI connects to, managed from a single screen. One account, complete control.

Common questions about Lob MCP in Pydantic AI

Install the MCP extra package and initialize `MCPToolset` with your Vinkius server URL. Pass this toolset into the `toolsets` argument of your Pydantic AI Agent constructor to register all 21 tools.

The framework raises a validation error at runtime rather than letting the agent proceed with bad data. This ensures your application fails loudly and safely before any physical mail is queued.

Yes. The agent calls `list_letters` or `get_letter` to fetch tracking numbers and delivery dates. The returned JSON is parsed directly into typed Python objects for safe handling.

Your agent can use `create_template` to register layouts and `list_templates` to retrieve them. Pydantic AI ensures the merge variables passed to `create_letter` match the template's expected schema.

All communication is proxied through Vinkius's zero-trust V8 isolates. Your recipient names, mailing addresses, and check amounts are processed in ephemeral memory and never persisted on Vinkius servers.

Use it with your favorite AI tools

Connect this server to Cursor, Claude, VS Code, and more.

OpenAI Agents SDK sdk-python

Google ADK sdk-python

Pydantic AI sdk-python

Vercel AI SDK sdk-typescript